diff --git a/modules/interfaces/interfaceComponentObjects.py b/modules/interfaces/interfaceComponentObjects.py
index edba0a66..59b10ddf 100644
--- a/modules/interfaces/interfaceComponentObjects.py
+++ b/modules/interfaces/interfaceComponentObjects.py
@@ -350,6 +350,9 @@ class ComponentObjects:
         # If fileName is provided, check for exact name+hash match first
         if fileName:
             for file in accessibleFiles:
+                # Skip files without fileName key or with None/empty fileName
+                if "fileName" not in file or not file["fileName"]:
+                    continue
                 if file["fileName"] == fileName:
                     return FileItem(
                         id=file["id"],
@@ -361,16 +364,24 @@ class ComponentObjects:
                         creationDate=file["creationDate"]
                     )
         
-        # Return first file with matching hash (for general duplicate detection)
-        return FileItem(
-            id=accessibleFiles[0]["id"],
-            mandateId=accessibleFiles[0]["mandateId"],
-            fileName=accessibleFiles[0]["fileName"],
-            mimeType=accessibleFiles[0]["mimeType"],
-            fileHash=accessibleFiles[0]["fileHash"],
-            fileSize=accessibleFiles[0]["fileSize"],
-            creationDate=accessibleFiles[0]["creationDate"]
-        )
+        # Return first valid file with matching hash (for general duplicate detection)
+        for file in accessibleFiles:
+            # Skip files without fileName key or with None/empty fileName
+            if "fileName" not in file or not file["fileName"]:
+                continue
+            # Use first valid file
+            return FileItem(
+                id=file["id"],
+                mandateId=file["mandateId"],
+                fileName=file["fileName"],
+                mimeType=file["mimeType"],
+                fileHash=file["fileHash"],
+                fileSize=file["fileSize"],
+                creationDate=file["creationDate"]
+            )
+        
+        # If no valid files found, return None
+        return None
 
     def getMimeType(self, fileName: str) -> str:
         """Determines the MIME type based on the file extension."""
@@ -454,15 +465,23 @@ class ComponentObjects:
         fileItems = []
         for file in filteredFiles:
             try:
+                # Ensure proper values, use defaults for invalid data
+                creationDate = file.get("creationDate")
+                if creationDate is None or not isinstance(creationDate, (int, float)) or creationDate <= 0:
+                    creationDate = get_utc_timestamp()
+                
+                fileName = file.get("fileName")
+                if not fileName or fileName == "None":
+                    continue  # Skip records with invalid fileName
+                
                 fileItem = FileItem(
                     id=file.get("id"),
                     mandateId=file.get("mandateId"),
-                    fileName=file.get("fileName"),
+                    fileName=fileName,
                     mimeType=file.get("mimeType"),
-                    workflowId=file.get("workflowId"),
                     fileHash=file.get("fileHash"),
                     fileSize=file.get("fileSize"),
-                    creationDate=file.get("creationDate")
+                    creationDate=creationDate
                 )
                 fileItems.append(fileItem)
             except Exception as e:
@@ -511,6 +530,9 @@ class ComponentObjects:
         
         # Check if fileName exists (excluding the current file if updating)
         for file in files:
+            # Skip files without fileName key or with None/empty fileName
+            if "fileName" not in file or not file["fileName"]:
+                continue
             if file["fileName"] == fileName and (excludeFileId is None or file["id"] != excludeFileId):
                 return False
         return True
@@ -544,9 +566,12 @@ class ComponentObjects:
         fileSize = len(content)
         fileHash = hashlib.sha256(content).hexdigest()
         
+        # Ensure mandateId is valid
+        mandateId = self.currentUser.mandateId or "default"
+        
         # Create FileItem instance
         fileItem = FileItem(
-            mandateId=self.currentUser.mandateId,
+            mandateId=mandateId,
             fileName=uniqueName,
             mimeType=mimeType,
             fileSize=fileSize,
diff --git a/modules/routes/routeDataFiles.py b/modules/routes/routeDataFiles.py
index 7f63dac4..2be59f21 100644
--- a/modules/routes/routeDataFiles.py
+++ b/modules/routes/routeDataFiles.py
@@ -86,13 +86,13 @@ async def upload_file(
             )
         
         # Save file via LucyDOM interface in the database
-        fileItem, duplicateType = managementInterface.saveUploadedFile(fileContent, file.fileName)
+        fileItem, duplicateType = managementInterface.saveUploadedFile(fileContent, file.filename)
         
         # Determine response message based on duplicate type
         if duplicateType == "exact_duplicate":
-            message = f"File '{file.fileName}' already exists with identical content. Reusing existing file."
+            message = f"File '{file.filename}' already exists with identical content. Reusing existing file."
         elif duplicateType == "name_conflict":
-            message = f"File '{file.fileName}' already exists with different content. Uploaded as '{fileItem.fileName}'."
+            message = f"File '{file.filename}' already exists with different content. Uploaded as '{fileItem.fileName}'."
         else:  # new_file
             message = "File uploaded successfully"
         
@@ -110,7 +110,7 @@ async def upload_file(
             "message": message,
             "file": fileMeta,
             "duplicateType": duplicateType,
-            "originalFileName": file.fileName,
+            "originalFileName": file.filename,
             "storedFileName": fileItem.fileName,
             "isDuplicate": duplicateType != "new_file"
         })
@@ -315,11 +315,15 @@ async def download_file(
             )
         
         # Return file as response
+        # Properly encode filename for Content-Disposition header to handle Unicode characters
+        import urllib.parse
+        encoded_filename = urllib.parse.quote(fileData.fileName)
+        
         return Response(
             content=fileContent,
             media_type=fileData.mimeType,
             headers={
-                "Content-Disposition": f"attachment; fileName={fileData.fileName}"
+                "Content-Disposition": f"attachment; filename*=UTF-8''{encoded_filename}"
             }
         )
     except HTTPException: